A Dissertation 2019
The main objective of this study was to assess health risks that may be associated with
consumption of rice grown in three selected Wards of Rwamgasa, Magenge and Kaseme
in Geita District.The agricultural soils ofthese wards are thought to have been
contaminated with Mercury (Hg) used in amalgamation of Gold, and Arsenic (As)from
anthropogenic sources (Arsenopyrates). Rice samples were collected from 15 villages of
the selected Wards after which the concentrations of Hg and As were determined. The
Association of Official Agricultural Chemists (AOAC 2015.01) was used for
quantification of heavy metals.Macro Plasma Emission Spectroscopy (MP-AES 4210)
equipped ith Auto sampler SPS4 was used in this case to quantify Hg and As.
Concentrations (ppm) for each metal was significantly different (p<0.05) among sampling
locations. The concentration of Hg and As per kg of rice in the sampled villages ranged
from 0.78 mg/kg to 3.58 mg/kg at Rwamgasa and Mnekezi villages and 0.64 mg/kg to
1.01 mg/kg at Nyamalulu and Bingwa villages, respectively. Exposure analysis was
established in line with health risks characterization for adults of 65 kg and children with
30 kg average body weight in which the calculated exposure dietary intake (EDI) was
calculated. These results revealed that, concentration of Mercury exceeded the Maximum
Allowable Concentration (MAC) of 0.02 mg/kgbw/day as per Ministry of Healthy of
Health of the Republic of People of China (MHRPC). Further more, the health risk index
(HRI) was computed as per USEPA/IRIS (2013) in which, for Mercury the Health Risk
Index (HRI) exceeded 1 for children in villages of Rwamgasa, Iseni, Nyakayenze,
Magenge, Nyamtondo, Nyamalimbe and Msasa implying health risks to children but there
was no risks for adults. In the case of Arsenic it was observed that it did not pose health
risks in both age groupssince the concentration did not exceed the MAC of 0.35
mg/kgbw/day approved by FAO/WHO (2016).